Saori Noguchi, William E Boeglin, Ned A Porter, Alan R Brash
{"title":"亚油酸酯 9-过氧化氢(9-HPODE)在血红素催化下降解,通过一个拟议的假对称二环氧自由基中间体形成两个烯丙基环氧酮。","authors":"Saori Noguchi, William E Boeglin, Ned A Porter, Alan R Brash","doi":"10.1080/10715762.2024.2386459","DOIUrl":null,"url":null,"abstract":"<p><p>Heme-initiated decomposition of unsaturated fatty acid hydroperoxides creates alkoxyl radicals that propagate a complex series of reactions to hydroxy, keto, epoxy and aldehydic products. Herein, among the products from the hematin-catalyzed degradation of 9-hydroperoxy-linoleic acid (9-HPODE), we observed a double peak on normal-phase HPLC that resolved on RP-HPLC into equal proportions of two epoxy-allylic ketones with identical UV spectra. Their proton NMR spectra were also indistinguishable and consistent with 9,10-<i>trans</i>-epoxy-11<i>E</i>-13-keto- and 9-keto-10<i>E</i>-12,13-<i>trans</i>-epoxy-octadecenoic acids. Acid hydrolysis to the corresponding dihydroxy-ketones and GC-MS analysis identified the earlier eluting product on RP-HPLC as the 9,10-epoxy regio-isomer. Starting from the C9-hydroperoxide, recovery of the two epoxy-ketones in equal proportions suggests their formation from a common intermediate. Earlier work has proposed formation of a pseudo-symmetrical diepoxy radical (9,10-epoxy-11(•)-12,13-epoxy, derived from an epoxy allylic hydroperoxide precursor) in the carbon chain fragmentation leading to aldehydic products. This intermediate in pathways of alkoxyl radical reactions forms equal pairs of aldehydes, and now also a pair of epoxy-ketones, and based on mechanism the same products arise from either 9-HPODE or 13-HPODE. Our results point to the intermediacy of this diepoxy-carbinyl radical in the origin of at least two classes of linoleate peroxidation products, and it should be considered as a viable intermediate for homo-conjugated diene peroxidation in general. The reactions could contribute to the aldehydes and epoxy-ketones in tissues undergoing oxidative transformations of polyunsaturated fatty acids.</p>","PeriodicalId":12411,"journal":{"name":"Free Radical Research","volume":null,"pages":null},"PeriodicalIF":3.6000,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11360661/pdf/","citationCount":"0","resultStr":"{\"title\":\"Heme-catalyzed degradation of linoleate 9-hydroperoxide (9-HPODE) forms two allylic epoxy-ketones via a proposed pseudo-symmetrical diepoxy radical intermediate.\",\"authors\":\"Saori Noguchi, William E Boeglin, Ned A Porter, Alan R Brash\",\"doi\":\"10.1080/10715762.2024.2386459\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Heme-initiated decomposition of unsaturated fatty acid hydroperoxides creates alkoxyl radicals that propagate a complex series of reactions to hydroxy, keto, epoxy and aldehydic products. Herein, among the products from the hematin-catalyzed degradation of 9-hydroperoxy-linoleic acid (9-HPODE), we observed a double peak on normal-phase HPLC that resolved on RP-HPLC into equal proportions of two epoxy-allylic ketones with identical UV spectra. Their proton NMR spectra were also indistinguishable and consistent with 9,10-<i>trans</i>-epoxy-11<i>E</i>-13-keto- and 9-keto-10<i>E</i>-12,13-<i>trans</i>-epoxy-octadecenoic acids. Acid hydrolysis to the corresponding dihydroxy-ketones and GC-MS analysis identified the earlier eluting product on RP-HPLC as the 9,10-epoxy regio-isomer. Starting from the C9-hydroperoxide, recovery of the two epoxy-ketones in equal proportions suggests their formation from a common intermediate. Earlier work has proposed formation of a pseudo-symmetrical diepoxy radical (9,10-epoxy-11(•)-12,13-epoxy, derived from an epoxy allylic hydroperoxide precursor) in the carbon chain fragmentation leading to aldehydic products. This intermediate in pathways of alkoxyl radical reactions forms equal pairs of aldehydes, and now also a pair of epoxy-ketones, and based on mechanism the same products arise from either 9-HPODE or 13-HPODE. Our results point to the intermediacy of this diepoxy-carbinyl radical in the origin of at least two classes of linoleate peroxidation products, and it should be considered as a viable intermediate for homo-conjugated diene peroxidation in general. The reactions could contribute to the aldehydes and epoxy-ketones in tissues undergoing oxidative transformations of polyunsaturated fatty acids.</p>\",\"PeriodicalId\":12411,\"journal\":{\"name\":\"Free Radical Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.6000,\"publicationDate\":\"2024-05-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11360661/pdf/\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Free Radical Research\",\"FirstCategoryId\":\"99\",\"ListUrlMain\":\"https://doi.org/10.1080/10715762.2024.2386459\",\"RegionNum\":3,\"RegionCategory\":\"生物学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"2024/8/4 0:00:00\",\"PubModel\":\"Epub\",\"JCR\":\"Q2\",\"JCRName\":\"BIOCHEMISTRY & MOLECULAR BIOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Free Radical Research","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1080/10715762.2024.2386459","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/8/4 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
Heme-catalyzed degradation of linoleate 9-hydroperoxide (9-HPODE) forms two allylic epoxy-ketones via a proposed pseudo-symmetrical diepoxy radical intermediate.
Heme-initiated decomposition of unsaturated fatty acid hydroperoxides creates alkoxyl radicals that propagate a complex series of reactions to hydroxy, keto, epoxy and aldehydic products. Herein, among the products from the hematin-catalyzed degradation of 9-hydroperoxy-linoleic acid (9-HPODE), we observed a double peak on normal-phase HPLC that resolved on RP-HPLC into equal proportions of two epoxy-allylic ketones with identical UV spectra. Their proton NMR spectra were also indistinguishable and consistent with 9,10-trans-epoxy-11E-13-keto- and 9-keto-10E-12,13-trans-epoxy-octadecenoic acids. Acid hydrolysis to the corresponding dihydroxy-ketones and GC-MS analysis identified the earlier eluting product on RP-HPLC as the 9,10-epoxy regio-isomer. Starting from the C9-hydroperoxide, recovery of the two epoxy-ketones in equal proportions suggests their formation from a common intermediate. Earlier work has proposed formation of a pseudo-symmetrical diepoxy radical (9,10-epoxy-11(•)-12,13-epoxy, derived from an epoxy allylic hydroperoxide precursor) in the carbon chain fragmentation leading to aldehydic products. This intermediate in pathways of alkoxyl radical reactions forms equal pairs of aldehydes, and now also a pair of epoxy-ketones, and based on mechanism the same products arise from either 9-HPODE or 13-HPODE. Our results point to the intermediacy of this diepoxy-carbinyl radical in the origin of at least two classes of linoleate peroxidation products, and it should be considered as a viable intermediate for homo-conjugated diene peroxidation in general. The reactions could contribute to the aldehydes and epoxy-ketones in tissues undergoing oxidative transformations of polyunsaturated fatty acids.
期刊介绍:
Free Radical Research publishes high-quality research papers, hypotheses and reviews in free radicals and other reactive species in biological, clinical, environmental and other systems; redox signalling; antioxidants, including diet-derived antioxidants and other relevant aspects of human nutrition; and oxidative damage, mechanisms and measurement.